Pope John Paul II should commission a churchwide study of clerical sex abuse to help prevent such acts and their cover-up in the future, Sydney Auxiliary Bishop Geoffrey Robinson has said.

Robinson, who helped write the church's sex abuse policy in Australia, said the recent US-Vatican summit was beneficial because it made the Vatican think about the issue and prompted a strong papal statement against abuse.

But Catholics and victims of abuse now want to see deeds, not words, he said in an e-mailed response to questions from the US-based Catholic News Service.

"I believe that the church will regain credibility on this issue only when the pope sets in train (motion) a truly serious, open and objective study into any and all factors within the church that might in any way contribute to a climate where abuse can occur or be covered up when it has occurred," said Bishop Robinson.